Preparation of dithianes



United States Patent O PREPARATION-F DITHIANES Nathaniel L. Remes, "Elgim and William A. *Krewer, Arlington- Heights, 111., 'assignors' to *The Pure 'Oil Company; Chicago, lll.,-a' corporation of Ohio No Drawing. Application December 2ll, 1955 Serial No. 554,139

-6 Claims. 01. 260-327) This invention relates to the preparation of sulfur-containing, heterocyclic compounds. It is more specifically concerned with the synthesis of .heterocyclic hydrocarbons having two sulfur atoms in a hexatomic ring.

It is known that the sulfur analogue of dioxane, dithiane, as' we'll as substituted 'dithianes' have a variety of uses.

For example, addition compounds ofdithiane and metallicsalts corresponding to dioxane' addition compounds have' been prepared. Dithianes also have certain end. applications without further reaction with Compounds of this nature are useful as chemical intermediates.

2,900,392 I Patented Aug. 18,1959

- 2 According to this invention, it has been found that dithianes and substituted dithianes may be prepared by reactingS-an inorganic thiocyanate'with' an epi-compound,

containing at least'five carbon'atoms'per molecule'and at least one hetero atom selected from the'group consi'sting ofioxygen and sulfur attached to'twodir'ectly connected'carbon atoms in the carbon chain,iin the presence of amutual solvent whichprov'ides at least partial miscibility of-the two" components of the reaction"system,'under atmospheric," superatmospheric, or subatmospheric 'pres- "sure, and at temperatures from about 50-200 C.

' The following specific examples illustrate suitable applications of 'thefiin'stant invention and'fishow the results obtained thereby. I It is to be understood that these examples are, given for illustrative purposes and are'not} intended to 'placeanyrestrictionsorlimitations" on the subject inother chemical compounds, and may be used per se as lubricating oil additives. for imparting extreme pressure characteristics to lubricating mineral oils, as plasticizers for use in the preparation of-synthetic and natural high molecular weight elastomers or polymers, etc. Thereare synthesizing dithianes having the formula:

organic radicals. It is knownthatolefins may be treated with sulfur dichloride and: further -reacted with sodium sulfide to-yield 1,4-dithianes (Glavis, Ryden and Marvel, J. Am. Chem. Soc., 59, 707 (1937)). "Another reaction involving the use of sodium-sulfideas thesulfurizing agentinvolves the treatmentof organic dibromid'e's with sodium sulfide (Garvilov andTischenko, 1. Gem; Chem. (USSR), 17, 967 (1947)). Some Work has also been reported on the" :llSeIOf-T 'a'ctivatedalumina for catalyzing dithiane synthesis reactions. For example, this .catalys-t has been used in promoting the reaction between ethylene oxide and hydrogen sulfide at temperatures of about 200 C. to produce dithiane (Doklady Akad. Nauk (USSR), 63, 285 (1948)). Other reactants, which will interact with hydrogen sulfide in the presence of alumina at temperatures of 200-400 C. to produce dithianes, include thiodiethylene glycol and p-oxathiane (Y. Yureva and K. Noutskii, Chem. Ab., 44, 1904 (1950)).

In US. Patent 2,094,837 there is described the preparation of alkylene sulfides by reacting alkylene oxide and a salt of thiocyanic acid at low temperatures. It has now been found that dithianes may be prepared by reacting alkylene oxides or alkylene sulfides containing at least five carbon atoms, with an inorganic thiocyanate under certain reaction conditions.

Accordingly, it is an object of this invention to provide a practical and economical method for the production of dithianes. This and other objects will be more apparent from the following detailed description of the instant invention.

available in theiprioriart a number of"proceduresfor vention.

. Example 1 A mixture of 9.1 grams of 1,2-epoxydodecane, 7.3 grams of potassium thiocyanate, and-30 ml. of methanol 7 were heated :under refluxar a: temperature of 66 C. for five hours. The mixture waspoured into'water, extracted with benzene, the benzene extract'was washedwith-water, and then the -benzene-was removed' by-distillation. Distillation of the residue yielded-asrnallquantity oflow-boil- =.ing mate-rialand-'4;0; grams of 2,5-didecyl-1,4-dithiane -(B-.P.'235-240 at 1.7 mm; pressure).

"Example 2 A mixture of 27 .3sgrams of 1,2-epoxydodecane, 21.3

- grams ofpotassium thiocyanate, and 150..-ml. of 90:% ethanol was heatedunder reflux at-a temperature of 78 C. After six hours,-half of the reactionmass was removed and-furtherprocessed as in Example 1;: the remainder of the mass-was refluxed ata temperature of'78 --C. for 24 hom's, andwas then treatedasin'Example 1.

- From the six-hour product, 1.7 grams of forerun mate .rial ('nfi '-1.4575), boiling from 66-1453 C.- at- 3mm. Hg, and 4.6-gramsof 2;5-didecyl 1,4-dithiane, boiling at 210-245" C. at 2.7 mmpHg (11 1.4873), were obtained. From the 24-hour portion,4'.3" grams of forerun distillate boiling =-within the range of 94-190 Cu-at 35-4 mm.

(n 1.4575 ,and 11.3 grams of- 2,5-didecy1- 1,4 dithiane,

' boiling principally: at 242-246 C. at 2.4-2.8

(11 5 1.4869), were obtained.

7 Example 3 Ten grams of 1,2-epithiododecane, 7.2 grams of, potassium .thiocyanate, andl00 m1. of ethanol were refluxed ata-temperature arts" C. for-four-hours -and About 2.9 grams of: 2,5-

255 C. at 2.4 mm. Hg (h 1.4919),from the unreacted dodecene sulfide.

A redistilled sample of the 2,5 didecyl-l,4-dithiane boiled at 241-250 C. at 1.7 mm. (n 1.4875). The empirical formula for this compound is C H S giving a theoretical sulfur content of 16.0%. The sulfur content of the product purified by redistillation was analytically determined as 15.7%. The empirical formula, C H S represents a molecular weight of 400. The molecular weight of the purified product, as determined cryoscopically in benzene, was 375. These results leave no doubt that 0 1-1 8 is the correct empirical formula. From structural considerations, scission of the C-S bond in 1,2- epithiododecane must result in the production of a 1,2- or a 1,4-dithiane and the latter is considered more probable.

As will be apparent from the foregoing description an illustrative examples, the instant invention provides practical method for the production of dithianes ori stituted dithianes. The five carbon atom epi-compou which may be employed in carrying out the instant invention are represented by the following formula:

where X is a hetero atom selected from the group consisting of sulfur and oxygen and R and R are substituent groups which may be alkyl, aryl, alkylene or hydrogen, or non-hydrocarbon substituents, such as sulfur-containing groups, nitriles, carboxyl derivatives, such as esters, others, or other functional groups which are unreactive in the presence of alkali metal thiocyanates. Typical epicompounds, containing at least five carbon atoms per molecule, which may be used in accordance with this invention include alkylene sulfides, such as a-amylene sulfide and 2,4,4-tn'methyl-2,3-epithiopentane, and ,alkylene oxides, such as 1,2-epoxyhexane and 2,4,4-trimethyl-2,3-

epoxypentane. Exemplary of the unsaturated episulfides and oxides which may be employed in carrying out the instant invention are isopropene monoxide, etc. In addition, sulfides or oxides of cyclic compounds, including alicyclic compounds, such as cyclohexene sulfide, as well as aromatic derivatives of ethylene sulfide, such as styrene oxide and stil'bene oxide, can be utilized. Examples of epi-compounds containing substituents such as ethers, nitriles, etc., include but are not limited to the glycidol derivatives and thioglycidol derivatives, such as allyl glycidol ether, butyl glycidol ether, diglycidol ether, 3-cyano- 1,2-epoxybutane, etc., or mixtures thereof.

In order to produce the dithianes of this invention, the subject reaction must be carried out at. a temperature of not less than about 50 C. It has been found that suitable yields may be produced employing temperatures'from about 64 C.-200 C. To provide a substantially homogeneous reaction system, it is preferred that the reaction be conducted in the presence of a suitable mutual solvent. The selected solvent must be non-reactive with the components of the reaction system, i.e. alkylene epoxide and/ or sulfide, and inorganic thiocyanate, and provide at least partial miscibility between the reactants. Examples of suitable solvents include water, ethanol, ethylene and propylene glycol, N,N-dimethyl formamide, 2-ethoxyethanol, diethyleneglycol ethyl ether, etc. While the above-named solvents are eifeotive, methanol and ethanol have been found to be especially suitable.

Inorganic thiocyanates which are utilized in this invention are those which will provide a reactive thiocyanate radical. Salts of thiocyanic acid which can be employed for this purpose include, but are not limited to, the alkali and alkaline earth metals, ammonium, zinc, manganese, iron, and other thiocyanates. The reactants are employed in about equimolar proportions, preferably with an excess of the thiocyanate being present. However, other proportions of reactants may be used, if desired.

While it is preferred to carry out the reaction at atmospheric pressures, it also may be carried out under pressures substantially above or below normal atmospheric pressure. The reaction time, of course, will depend upon the nature of the materials being employed, as well as their respective amounts and the temperature of the reaction. In general, however, it has been found that a reaction period from about 6-24 hours will produce substantial amounts of the desired product.

In recovering the reaction products from the reaction mixture, the dithiane is separated either by filtration or extraction with a water-immiscible, organic solvent in which the dithiane is soluble. Suitable solvents include benzene, petroleum hexane, ether, toluene, etc.

We claim as our invention:

1. A method for preparing substituted dithianes which comprises heating an epi-compound containing at least five carbon atoms per molecule, and having the general formula R-o7oH.-R'

Where X is selected from the group consisting of oxygen and sulfur, R is selected from the group consisting of alkyl and aryl radicals, and R is selected from the group consisting of hydrogen, alkyl, and aryl radicals, with at least an equimolar amount of a compound selected from the group consisting of metal thiocyanates and ammonium thiocyanate, to a temperature in the range from about 50 to 200 C., in solution in a mutual solvent for the reactants, and recovering a dithiane of the formula R ca-o n-n where the R and R groups are as hereinbefore defined.

References Citedin the file of this patent UNITED STATES PATENTS 1,018,329 Lilienfeld Feb. 20, 1912 2,094,837 Dachlauer Oct. .5, 1937 2,094,914 Dachlauer Oct. 5, 1937 2,183,860 Coltof Dec. 19, 1939 2,346,157 Farrington -Q. Apr. 11, 1944 OTHER REFERENCES Masson: J. Chem. Soc., vol. 49, pp. 234-237 (1886). 

1. A METHOD FOR PREPARING SUBSTITUTED DITHIANES WHICH COMPRISES HEATING AN EPI-COMPOUND CONTAINING AT LEAST FIVE CARBON ATOMS PER MOLECULE, AND HAVING THE GENERAL FORMULA 